a. Field of the Invention
This invention relates generally to telephony, and more particularly to a method and system for detecting each time a party is added to a previously recorded or live telephone call.
b. Background Art
There is a general need for systems that detect three way calls. Many types of systems exist that detect three way calls by measuring certain line characteristics such as voltage fluctuations, noise and other electromechanical characteristics.
The purpose of many conventional three way call detection systems is to automatically disconnect an existing telephone connection whenever a three way call is detected. For example, correctional facilities such as jails and prisons routinely monitor or record telephone conversations of inmates. Inmates in general are prohibited from making three way telephone calls because these calls have been found to be made in order to, for instance, inappropriately contact witnesses or to call individuals that they would otherwise be prohibited from calling, such as convicted felons, drug dealers and gang members.
Although most correctional facilities record all telephone calls made by inmates, it is believed that on average only a very small proportion is ever monitored by correctional officers. Many correctional facilities record 2,000 inmate telephone calls a day, so monitoring all telephone calls or even a large fraction on a regular basis would require too much personnel and would be cost prohibitive. Inmates are aware of this and know that there is little chance of getting caught making a three way call. Thus, many make three way calls on a routine basis without being detected.
It is desirable in some instances to allow the completion of three way calls for intelligence gathering purposes because such calls often contain evidence of wrongdoing, such as terrorist or criminal activity, or other valuable information. Simply disconnecting an inmate as soon as a three way call is detected could result in the loss of potentially valuable information in those cases where an inmate is suspected of using telephones to engage in illegal or improper activity.